JP5156612B2 - Organic electroluminescence device and method for producing the same - Google Patents

Description

  The present invention relates to an organic electroluminescence element (hereinafter sometimes referred to as an organic EL element), a method for producing the organic EL element, an illumination device using the organic EL element, a planar light source, and a display device.

  In recent years, the use of organic EL in display devices and lighting devices has been studied. The organic EL element includes, for example, a pair of electrodes and a light emitting layer in which an organic fluorescent dye is dispersed, and emits light with a predetermined spectrum by applying a voltage between the electrodes. As a light emitting element that emits white light, an organic EL element including a white light emitting layer in which a plurality of types of pigments are dispersed is disclosed (for example, see Patent Document 1).

  By changing the voltage applied to the organic EL element, the luminance (amount of light emission) of the organic EL element can be adjusted, but the color of the emitted light also changes accordingly. Therefore, in the lighting device using the organic EL element, the color of the illumination changes according to the brightness. In the display device using the organic EL element for the light source or backlight of the pixel, the display image is changed according to the brightness. The hue will change. Therefore, there is a demand for an organic EL element that hardly changes in color with respect to a change in voltage.

  As a light emitting element, a light emitting element with high luminous efficiency is naturally required. Light generated inside the organic EL element is totally reflected by an electrode or absorbed inside and confined inside the element. However, most of them are not used effectively. Therefore, as an attempt to improve the light emission efficiency by improving the light extraction efficiency, a light scattering layer is provided between the transparent substrate on which the organic EL element is provided and the electrode of the organic EL element, so that the total reflection of light is achieved. In order to improve light extraction efficiency (see, for example, Patent Document 2).

Japanese Patent Application Laid-Open No. 07-220871 JP 2007-035550 A

  However, even in the organic EL element of the prior art, the light emission efficiency is not always sufficient.

  The present invention has been made in view of the above-described problems in the prior art, and its problem is an organic EL element having a small change in color with respect to a change in voltage applied to an electrode and having high luminous efficiency, and a method for manufacturing the same. And providing an illumination device, a planar light source, and a display device using the organic EL element.

In order to solve the above problems, the present invention employs the following configuration.
[1] A first electrode that is one of an anode and a cathode and has optical transparency;
A second electrode disposed opposite to the first electrode and being the other of the anode and the cathode;
A light emitting part disposed between the first electrode and the second electrode and having three or more light emitting layers containing a polymer compound;
A film disposed on the outermost layer on the first electrode side with respect to the light emitting part, and
Each light emitting layer constituting the light emitting part emits light having a different peak wavelength, and the light emitting layer emitting light having a longer peak wavelength is disposed closer to the anode,
The film has an uneven surface on the side opposite to the light emitting part side, has a haze value of 70% or more, and a total light transmittance of 80% or more.
Organic electroluminescence device.
[2] The organic electroluminescence element according to [1], wherein the light emitting unit includes a light emitting layer that emits red light, a light emitting layer that emits green light, and a light emitting layer that emits blue light.
[3] It further includes a support substrate provided between the first electrode and the film,
The organic electroluminescent element according to the above [1] or [2], wherein the film is provided in contact with the support substrate.
[4] It further has a protective film provided between the first electrode and the film,
The organic electroluminescence element according to the above [1] or [2], wherein the film is provided in contact with the protective film.
[5] When the voltage applied between the anode and the cathode is changed, the width of the change between the coordinate value x and the coordinate value y in the chromaticity coordinates of the light extracted outside is 0, respectively. The organic electroluminescence device according to any one of [1] to [4], which is 0.05 or less.
[6] The organic electroluminescent element according to any one of [1] to [5], wherein a surface of the film opposite to the light emitting layer side is configured by a plurality of concave surfaces.
[7] A planar light source including the organic electroluminescence element according to any one of [1] to [5].
[8] An illumination device including the organic electroluminescence element according to any one of [1] to [5].
[9] A display device comprising the organic electroluminescence element according to any one of [1] to [5].
[10] One of an anode and a cathode, a first electrode having light transmissivity, and the other electrode of the anode and the cathode disposed opposite to the first electrode A second electrode, a light emitting part disposed between the first electrode and the second electrode and having three or more light emitting layers containing a polymer compound; and an outermost layer on the first electrode side based on the light emitting part A method for producing an organic electroluminescence device comprising a film disposed on
Forming each light emitting layer sequentially by a coating method so that the light emitting layer emitting light having a long peak wavelength is disposed closer to the anode;
A film forming step of forming a film on the opposite side of the light emitting part side, having a concavo-convex shape, having a haze value of 70% or more and a total light transmittance of 80% or more,
In the film forming step, a solution containing the material to be the film is applied onto the surface on which the film is formed so that the thickness of the film is in the range of 100 μm to 200 μm, and the applied solution is applied. After holding in an atmosphere with a humidity of 80% to 90%, it is dried to form a film.
Manufacturing method of organic electroluminescent element.

  ADVANTAGE OF THE INVENTION According to this invention, the organic EL element with little luminous change with respect to the change of the voltage applied to an electrode and high luminous efficiency is realizable. Therefore, the organic EL element of the present invention can be suitably used as a display device such as a lighting device, a planar light source as a backlight, and a flat panel display.

  Embodiments of the present invention will be described below with reference to the drawings. For ease of understanding, the scale of each member in the drawing may differ from the actual scale. Further, the present invention is not limited by the following description, and can be appropriately changed without departing from the gist of the present invention. In the organic EL device, there are members such as electrode lead wires. However, in the explanation of the present invention, the description is omitted because it is not directly required. For the convenience of explanation of the layer structure and the like, in the example shown below, the explanation is made with the figure in which the substrate is arranged below. However, the organic EL element of the present invention and the organic EL device equipped with the same are necessarily manufactured in this arrangement. Or use etc. are not made. In the following description, one of the support substrate in the thickness direction may be referred to as “upper” or “upper”, and the other of the support substrate in the thickness direction may be referred to as “lower” or “lower”.

  The organic EL device according to the present invention is one of an anode and a cathode, and is disposed opposite to the first electrode having light transmissivity and the first electrode. A second electrode that is the other of the first electrode, a light emitting part that is disposed between the first electrode and the second electrode, and has three or more light emitting layers containing a polymer compound, and the light emitting layer as a reference A light-emitting layer that emits light having a different peak wavelength, and that emits light having a longer peak wavelength, the light-emitting layer including the film disposed on the outermost layer on the first electrode side. The film has an uneven surface on the side opposite to the light emitting part side, the haze value of the film is 70% or more, and the total light transmittance of the film is 80% or more. It is characterized by that.

[First Embodiment]
A first embodiment of an organic EL element and its modification will be described with reference to FIG. FIG. 1 is a front cross-sectional view showing a first embodiment of the organic EL element of the present invention.
As a substrate constituting the organic EL element 1, there is a flat transparent support substrate 2 having light transmittance. On this transparent support substrate 2, a transparent anode 3 is disposed as a first electrode having light permeability. A light emitting section 4 is disposed on the transparent anode (first electrode) 3, and a cathode (second electrode) 5 is disposed thereon. The transparent support substrate 2 has a first main surface 2a and a second main surface 2b, and a light emitting function unit 6 including a transparent anode (first electrode) 3, a light emitting unit 4, and a cathode (second electrode) 5 is A transparent anode (first electrode) 3, a light emitting unit 4, and a cathode (second electrode) 5 are mounted in this order from the vicinity of one main surface 2 a. Usually, a protective film (sometimes referred to as an upper sealing film) 7 that protects the entire light emitting function unit 6 is provided to protect the light emitting function unit 6 disposed on the transparent support substrate 2. A film 8 is provided on the second main surface 2b opposite to the light emitting part 4 side of the transparent support substrate 2, and the outermost layer on the transparent anode (first electrode) 3 side with respect to the light emitting part 4 Film 8 corresponds.
That is, the transparent support substrate 2 having the first main surface 2a and the second main surface 2b is interposed between the transparent anode (first electrode) 3 and the film 8, and the light emitting function section 6 is closer to the first main surface 2a. To the transparent anode (first electrode) 3, the light emitting section 4, and the cathode (second electrode) 5 in this order, and the film 8 is provided in contact with the second main surface 2b.
Here, the outermost layer refers to a layer provided on the outermost side on the transparent anode (first electrode) 3 side with respect to the light emitting portion 4 among the layers constituting the organic EL element 1. In the embodiment, since the transparent support substrate 2 is provided on the opposite side of the transparent anode (first electrode) 3 from the light emitting portion 4 side, the film 8 provided in contact with the transparent support substrate 2 is the outermost layer.
In this specification, “a light-transmitting support substrate” and “light-transmitting electrode” mean a support substrate and an electrode through which at least part of incident light is transmitted.

  In the present embodiment, the first electrode 3 is an anode and the second electrode 5 is a cathode. However, the stacking order of the light emitting functional units 6 is reversed, the first electrode is a cathode, and the second electrode is an anode. The present invention can be suitably applied even to an organic EL element that is.

<A> Light Emitting Unit The light emitting unit 4 is disposed between the first electrode and the second electrode, has three or more light emitting layers containing a polymer compound, and the light emitting layers constituting the light emitting unit are mutually connected. A light emitting layer that emits light having different peak wavelengths and emits light having a longer peak wavelength is disposed closer to the anode. In FIG. 1, the light emission part 4 has shown the case where it is comprised from three light emitting layers 9a, 9b, 9c from which the peak wavelength of light emission differs. In the arrangement of FIG. 1, the three light emitting layers 9a, 9b, and 9c are light emitting layers that emit red, green, and blue light, respectively.

  That is, in the configuration shown in FIG. 1, the light emitting unit 4 includes, in order from the transparent anode (first electrode) 3 side, a light emitting layer that emits red light (hereinafter sometimes referred to as a red light emitting layer) 9 a and a light emitting light that emits green light. A layer (hereinafter sometimes referred to as a green light-emitting layer) 9b and a light-emitting layer that emits blue light (hereinafter also referred to as a blue light-emitting layer) 9c are laminated in this order. The light emitting layers 9a, 9b, and 9c are laminated in this order from the transparent anode (first electrode) 3 side, and the light emitting layers that emit light having different peak wavelengths are arranged closer to the anode as the light emitting layer that emits light having a longer peak wavelength. By doing so, it is possible to manufacture an organic EL element that emits light with high efficiency and little change in color with respect to a change in voltage applied to the electrode.

The red light emitting layer 9a has the longest peak wavelength of the emitted light among the three light emitting layers 9a, 9b, and 9c constituting the light emitting unit 4, and thus is the most transparent among the three light emitting layers 9a, 9b, and 9c. The green light emitting layer 9b is disposed near the anode (first electrode) 3, and the three light emitting layers 9a, 9b, 9c are in the three light emitting layers 9a, 9b, 9c because the peak wavelength of the emitted light is the middle. The blue light emitting layer 9c has the shortest peak wavelength of the emitted light among the three light emitting layers 9a, 9b, 9c, so that it is the cathode of the three light emitting layers 9a, 9b, 9c. (2nd electrode) It arrange | positions near 5.
In addition, the peak wavelength which the light emitting layer which comprises the light emission part 4 light-emits is a wavelength which becomes the strongest light intensity when the emitted light is seen in a wavelength range.

  As the red light emitting layer 9a in the present embodiment, a peak wavelength of emitted light is, for example, 580 nm or more and 660 nm or less, preferably 600 or more and 640 nm or less. In addition, as the green light emitting layer 9b in the present embodiment, a light emitting light having a peak wavelength of, for example, 500 nm or more and 560 nm or less, preferably 520 nm or more and 540 nm or less is used. Moreover, as the blue light emitting layer 9c in this embodiment, the peak wavelength of light to be emitted is, for example, 400 nm or more and 500 nm or less, preferably 420 nm or more and 480 nm or less.

  When the light emitted from each of the three light emitting layers 9a, 9b, and 9c that emit light at such a peak wavelength is superimposed, white light is generated. Therefore, the light emitting unit 4 has a red light emitting layer 9a, a green light emitting layer 9b, and a blue light emitting device. The organic EL element 1 of the present embodiment configured by the layer 9c emits white light as a whole.

  Therefore, as in the organic EL element 1 according to the present embodiment, the three light emitting layers 9a, 9b, and 9c constituting the light emitting unit 4 are more transparent anodes (first electrodes) as the light emitting layer emits light having a longer peak wavelength. By arranging the light emitting layers in a predetermined order according to the peak wavelength of the emitted light, the color changes little with respect to the change in the voltage applied to the electrode and high efficiency. An organic EL element that emits light can be realized.

  Each light emitting layer 9a, 9b, 9c constituting the light emitting unit 4 is formed by a coating method in the present embodiment. In particular, in the present embodiment, each light emitting layer formed by coating is insolubilized in the coating solution to be applied before the coating solution for the light emitting layer to be formed next is applied on the surface. Specifically, before the green light emitting layer 9b is formed by a coating method, the red light emitting layer 9a is insolubilized, and before the blue light emitting layer 9c is formed by a coating method, the green light emitting layer 9b is insolubilized.

  In this embodiment, at least a part of the material constituting the light-emitting layer to be insolubilized is crosslinked by applying energy. After applying a coating solution containing such a material to form a film, it is possible to insolubilize the film by applying light or heat as energy and crosslinking.

  Note that the light emitting layer may be formed using a material that mainly forms the light emitting layer to be insolubilized, and a material that crosslinks when energy is applied. The light emitting layer may be formed using a material in which at least a part of the remaining material excluding the material mainly constituting the material crosslinks by applying energy. In the latter case, in addition to the material mainly constituting the light emitting layer, a crosslinking agent that is crosslinked by applying energy is further added to the coating solution.

  In addition, if the material which mainly comprises a light emitting layer can be bridge | crosslinked by applying energy, it is not necessary to add a crosslinking agent to a coating liquid.

  In the present embodiment, the material mainly constituting the light emitting layer is the material having the highest mass concentration in the light emitting layer, and among the materials constituting the light emitting layer, materials that emit fluorescence and / or phosphorescence (hereinafter referred to as light emission). It may be called material).

In the case of using a material that crosslinks by applying energy as a material mainly constituting the light emitting layer, a polymer compound that includes a group that crosslinks by applying energy (hereinafter referred to as a crosslinkable group) may be used.
Examples of the crosslinking group include a vinyl group. Specific examples of materials mainly constituting the light emitting layer include those using a polymer compound containing a residue obtained by removing at least one hydrogen atom from benzocyclobutane (BCB) in the main chain and / or side chain. be able to.

  In addition to the material mainly constituting the light emitting layer, the crosslinking agent added to the coating solution includes vinyl group, ethynyl group, butenyl group, acryloyl group, acryloylamino group, methacryloyl group, methacryloylamino group, vinyloxy group, vinylamino group. And a compound having a polymerizable substituent selected from the group consisting of a group, a silanol group, a cyclopropyl group, a cyclobutyl group, an epoxy group, an oxetanyl group, a diketenyl group, an epithio group, a lactonyl group, and a lactamnyl group. Oxetanyl group is a residue obtained by removing one hydrogen atom from oxetane, diketenyl group is a residue obtained by removing one hydrogen atom from diketene, epithio group is a residue obtained by removing one hydrogen atom from episulfide, and lactonyl group is a lactone A residue obtained by removing one hydrogen atom from a lactamnyl group means a residue obtained by removing one hydrogen atom from a lactam. As such a compound for a crosslinking agent, for example, a polyfunctional acrylate is preferable, and dipentaerythritol hexaacrylate (DPHA), trispentaerythritol octaacrylate (TPEA), and the like are more preferable.

Each light emitting layer 9a, 9b, 9c is made of an organic material that emits fluorescence and / or phosphorescence as a main component. As the organic substance, a low molecular compound and / or a high molecular compound is used, preferably a high molecular compound is used, and the light emitting layer is a high molecular compound having a polystyrene-equivalent number average molecular weight of 10 ³ or more and 10 ⁸ or less. It is preferable to include. In addition to the organic material, the light emitting layer may include an optional component such as a dopant. For example, the dopant is added for the purpose of improving the light emission efficiency or changing the light emission wavelength. Examples of the light emitting material mainly constituting each of the light emitting layers 9a, 9b, 9c include the following.

<A1> Dye-based luminescent material Examples of the dye-based luminescent material include cyclopentamine derivatives, tetraphenylbutadiene derivative compounds, triphenylamine derivatives, oxadiazole derivatives, pyrazoloquinoline derivatives, distyrylbenzene derivatives, diesters, and the like. List polymerized styrylarylene derivatives, pyrrole derivatives, thiophene ring compounds, pyridine ring compounds, perinone derivatives, perylene derivatives, oligothiophene derivatives, oxadiazole dimers, quinacridone derivatives, coumarin derivatives, and pyrazoline dimers. Can do.

<A2> Metal Complex Light-Emitting Material As a metal complex-based light-emitting material, the central metal has a rare earth metal such as Al, Zn, Be, or Tb, Eu, Dy, etc. Examples include metal complexes having a metal complex having an azole, thiadiazole, phenylpyridine, phenylbenzimidazole, quinoline structure, etc., such as metal complexes having light emission from a triplet excited state such as iridium complexes and platinum complexes. , An aluminum quinolinol complex, a benzoquinolinol beryllium complex, a benzoxazolyl zinc complex, a benzothiazole zinc complex, an azomethylzinc complex, a porphyrin zinc complex, a phenanthroline europium complex, and the like.

<A3> Polymer-based luminescent materials Examples of polymer-based luminescent materials include polyparaphenylene vinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives, polysilane derivatives, polyacetylene derivatives, polyfluorene derivatives, and polyvinylcarbazole derivatives. Can do.

  Examples of the light emitting material mainly constituting the red light emitting layer 9a include coumarin derivatives, thiophene ring compounds, and polymers thereof, polyparaphenylene vinylene derivatives, polythiophene derivatives, polyfluorene derivatives, etc. Can do. Among these, polymer materials such as polyparaphenylene vinylene derivatives, polythiophene derivatives, and polyfluorene derivatives are preferable.

  Examples of the material mainly constituting the green light emitting layer 9b include quinacridone derivatives, coumarin derivatives, thiophene ring compounds and their polymers, polyparaphenylene vinylene derivatives, polyfluorene derivatives, etc. among the above light emitting materials. . Of these, polymer materials such as polyparaphenylene vinylene derivatives and polyfluorene derivatives are preferred.

  Examples of the material mainly constituting the blue light emitting layer 9c include polymers of distyrylarylene derivatives and / or oxadiazole derivatives, polyvinylcarbazole derivatives, polyparaphenylene derivatives, polyfluorene derivatives, etc., among the above light emitting materials. be able to. Of these, polymer materials such as polyvinyl carbazole derivatives, polyparaphenylene derivatives, and polyfluorene derivatives are preferred.

<A4> Dopant material As the light emitting material mainly constituting each light emitting layer 9a, 9b, 9c, in addition to the above light emitting material, a dopant material is further added for the purpose of, for example, improving the light emission efficiency or changing the light emission wavelength. May be included. Examples of such dopant materials include perylene derivatives, coumarin derivatives, rubrene derivatives, quinacridone derivatives, squalium derivatives, porphyrin derivatives, styryl dyes, tetracene derivatives, pyrazolone derivatives, decacyclene, phenoxazone, and the like. In addition, the thickness of such a light emitting layer is usually about 20 mm or more and 2000 mm or less.

<A5> Method for Forming Light-Emitting Layer Each light-emitting layer 9a, 9b, 9c can be formed by, for example, a coating solution in which a light-emitting material mainly constituting each light-emitting layer 9a, 9b, 9c is dissolved in a solvent. it can. The solvent used for film formation from a solution is not particularly limited as long as it can dissolve a light emitting material mainly constituting each of the light emitting layers 9a, 9b, 9c. For example, chlorine, water, chloroform, methylene chloride, dichloroethane or the like List solvents, ether solvents such as tetrahydrofuran, aromatic hydrocarbon solvents such as toluene and xylene, ketone solvents such as acetone and methyl ethyl ketone, ester solvents such as ethyl acetate, butyl acetate, and ethyl cellosolve acetate, and water be able to.
Also, as a coating method for forming a light emitting layer, spin coating method, casting method, micro gravure coating method, gravure coating method, bar coating method, roll coating method, wire bar coating method, dip coating method, spray coating method, screen Examples thereof include a printing method, a flexographic printing method, an offset printing method, a coating method such as an inkjet printing method, a vacuum vapor deposition method, and a transfer method.

<A6> Method for Producing Light-Emitting Unit A method for producing the light-emitting unit 4 by sequentially laminating a red light-emitting layer 9a, a green light-emitting layer 9b, and a blue light-emitting layer 9c on the anode as in the organic EL element 1 shown in FIG. To do. First, the red light emitting layer 9a is formed. Specifically, a coating solution in which the material constituting the red light emitting layer 9a is dissolved is applied on the surface of the transparent anode (first electrode) 3 by a conventional coating method. Next, the coated red light emitting layer 9a is obtained by heating or irradiating the applied film with light. The red light emitting layer 9a thus crosslinked does not elute even when a coating solution is applied to form the green light emitting layer 9b.

  Next, the green light emitting layer 9b is formed. Specifically, a coating solution in which the material constituting the green light emitting layer 9b is dissolved is applied onto the surface of the red light emitting layer 9a by a conventional coating method. Next, the coated green light emitting layer 9b is obtained by heating or irradiating the applied film with light. The green light emitting layer 9b thus crosslinked does not elute even when a coating solution is applied to form the blue light emitting layer 9c.

  Next, a blue light emitting layer 9c is formed. Specifically, the blue light emitting layer 9c is obtained by applying a coating solution in which the material constituting the blue light emitting layer 9c described above is dissolved onto the surface of the green light emitting layer 9b by a conventional coating method and drying.

  In this way, when the light emitting layer to be applied is applied to the surface of the previously formed light emitting layer by insolubilizing the light emitting layer to which the coating liquid is applied in advance with respect to the coating liquid, It can prevent that the light emitting layer formed previously melt | dissolves. Thereby, control of the film thickness of each light emitting layer becomes easy, and each light emitting layer of the intended film thickness can be formed easily. Moreover, since each light emitting layer of the intended film thickness can be laminated | stacked easily, it can be set as the organic EL element which has the stable light emission performance.

  As for the film thickness of each light emitting layer 9a, 9b, 9c which comprises the light emission part 4, the one where a film thickness is thinner is preferable, so that the light emitting layer arrange | positioned at the transparent anode (1st electrode) 3 side. Specifically, it is preferable that the green light emitting layer 9b is thicker than the red light emitting layer 9a, and the blue light emitting layer 9c is thicker than the green light emitting layer 9b. More specifically, the film thickness of the red light emitting layer 9a is preferably 5 nm or more and 20 nm or less, more preferably 10 nm or more and 15 nm or less. The film thickness of the green light emitting layer 9b is preferably 10 nm or more and 30 nm or less, and more preferably 15 nm or more and 25 nm or less. Moreover, the film thickness of the blue light emitting layer 9c is preferably 40 nm or more and 70 nm or less, and more preferably 50 nm or more and 65 nm or less. Therefore, by setting the film thickness of each of the light emitting layers 9a, 9b, and 9c, light is emitted with higher efficiency with less change in color and lower driving voltage with respect to changes in voltage applied to the electrodes. An organic EL element can be realized.

  Note that the longer the peak wavelength of the emitted light, the lower the highest occupied molecular orbital (abbreviated HOMO) and the lowest unoccupied molecular orbital (abbreviated LUMO) of the compound constituting the light emitting layer. Therefore, in this embodiment, the light emitting layer made of a compound having a low HOMO and LUMO is arranged closer to the transparent anode (first electrode) 3. In this manner, the light emitting layer that is separated from the transparent anode (first electrode) 3 has an arrangement in which the HOMO and LUMO of the compound constituting the layer are sequentially increased, so that holes and electrons are efficiently transported in the light emitting portion 4. It is estimated that an organic EL element with little change in color and low driving voltage can be realized with respect to a change in voltage applied to the electrode.

In the organic EL element 1 having such a configuration, when the voltage applied between the anode and the cathode is changed, the change width of the coordinate value x and the coordinate value y in the chromaticity coordinates of the light extracted outside. However, an organic EL element of 0.05 or less can be realized. The range when varying the voltage applied is generally luminance 100 cd / m ² or more, the range to be 10000 cd / m ² or less, in the range of at least 4000 cd / m ² or more, the 6000 cd / m ² or less .

  Here, the light extracted outside is the light in which the light from each light emitting layer 9a, 9b, 9c is superimposed. In this specification, the chromaticity coordinates are defined in accordance with CIE1931 defined by the International Commission on Illumination (CIE).

  The light emitting unit 4 in the present embodiment is configured by laminating three light emitting layers 9a, 9b, and 9c, and emits white light as a whole. However, as a modification of the present embodiment, a light emitting layer that emits light having a wavelength different from that emitted from each of the light emitting layers 9a, 9b, and 9c is provided, for example, a light emitting unit that emits light having a wavelength different from white 4 may be configured. As yet another modification, the light emitting unit 4 may be configured by four or more light emitting layers. That is, the color of light emitted from each light emitting layer is appropriately selected according to the color of light extracted from each organic EL element.

  In addition, the color of light extracted from the organic EL element was white or a color different from white, and even if the number of layers of the light emitting unit 4 was 3, the number of layers was 4 or more. However, by arranging each light emitting layer closer to the transparent anode (first electrode) 3 as the light emitting layer that emits light having a longer peak wavelength, the change in color with respect to the change in voltage applied to the electrode can be reduced. An organic EL element that emits light with low efficiency and high efficiency can be realized.

<B> Film The film 8 is provided in the outermost layer on the transparent anode (first electrode) 3 side with respect to the light emitting portion 4, and in the present embodiment, on the side opposite to the light emitting portion 4 side of the transparent support substrate 2. Provided on the surface. The surface of the film 8 on the light emitting unit 4 side is flat, and the surface on the side opposite to the light emitting unit 4 side is formed in an uneven shape. The film 8 has a haze value of 70% or more and a total light transmittance of 80% or more.

  The planar surface of the film 8 is bonded to the outer surface (second main surface 2b) opposite to the light emitting unit 4 side of the transparent support substrate 2. The film 8 is affixed on the transparent support substrate 2 using bonding agents, such as a thermosetting resin, a photocurable resin, an adhesive agent, and an adhesive material, for example. When the thermosetting resin is used, the film 8 is bonded to the transparent support substrate 2 by bonding the film 8 to the transparent support substrate 2 and then heating at a predetermined temperature. Moreover, when using a photocurable resin, after bonding the film 8 to the transparent support substrate 2, the film 8 is adhere | attached on the transparent support substrate 2, for example by irradiating the film 8 with an ultraviolet-ray. In addition, when forming the film 8 directly on the transparent support substrate 2, and when the bonding agent is previously provided in the film 8, the said bonding agent does not need to be used.

  When an air layer is formed between the film 8 and the transparent support substrate 2, reflection occurs at the interface of the air layer, so that no air layer is formed between the film 8 and the transparent support substrate 2. It is preferable to bond the film 8 together. Of the refractive index of the film 8, the refractive index of the bonding agent, and the refractive index of the layer to which the film 8 is bonded (in this embodiment, the transparent support substrate 2), the maximum refractive index, and the minimum refractive index The smaller the difference is, the more preferable it is because reflection on the bonding surface can be suppressed. Specifically, the difference is preferably within 0.2, and more preferably within 0.1.

In the film 8 of the present embodiment, one surface of the film 8 (the surface on the side opposite to the light emitting portion 4 side after the film 8 is attached to the outer surface of the transparent support substrate 2) is formed in an uneven shape. The haze value is 70% or more, and the total light transmittance is 80% or more. If the haze value is less than 70%, a sufficient light scattering effect may not be obtained, and if the total light transmittance is less than 80%, sufficient light may not be extracted. When the film 8 is used for an organic EL element, there is a possibility that sufficient light extraction efficiency cannot be realized. Therefore, by using the film 8 having a haze value of 70% or more and a total light transmittance of 80% or more, an organic EL element with high extraction efficiency can be realized.
The haze value is represented by the following formula.
Haze value (cloudiness value) = (diffuse transmittance (%) / total light transmittance (%)) × 100 (%).
The diffuse transmittance is the ratio of the radiant flux or light beam incident on the diffusely transmitted material to the radiant flux or light beam incident on the material. The haze value can be measured by the method described in JIS K 7136 “Plastic—How to Obtain Haze of Transparent Material”.
The total light transmittance can be measured by the method described in JIS K 7361-1 “Testing method of total light transmittance of plastic-transparent material”.

  If the size (width) of the convex surface or concave surface in the width direction perpendicular to the thickness direction of the film 8 is too large, the luminance on the surface of the film 8 becomes nonuniform, and if it is too small, the production cost of the film 8 increases. Therefore, it is preferably 0.5 μm or more and 20 μm or less, and more preferably 1 μm or more and 2 μm or less. Further, the height of the convex surface or concave surface in the thickness direction of the film 8 is determined by the size (width) of the convex surface or concave surface in the width direction and the period in which the concave and convex shapes are formed, and usually the concave surface or convex surface in the width direction. Or less than the period (width) or the period in which the concavo-convex shape is formed is preferably 0.25 μm or more and 10 μm or less, and preferably 0.5 μm or more and 1.0 μm or less.

  Although there is no restriction | limiting in particular in the shape of a convex surface or a concave surface, What has a curved surface is preferable, for example, a hemispherical shape is preferable. The concave surface or the convex surface is preferably arranged regularly, for example, preferably arranged in a grid pattern. Moreover, 60% or more of the area of the surface of the film 8 is preferable in the area where the concave surface and the convex surface are formed in the surface of the film 8.

  The material which comprises the film 8 should just be a material which can satisfy | fill a haze value and a total light transmittance, when it shape | molds in the film 8, and there is no restriction | limiting in particular. As a material constituting the film 8, for example, a polymer material and glass may be used. Examples of the polymer material constituting the film 8 include polyarylate, polycarbonate, polycycloolefin, polyethylene naphthalate, polyethylene sulfonic acid, and polyethylene terephthalate. The film 8 includes a support made of, for example, the above-described polymer material and glass, and a thin film formed on the surface of the support, the surface opposite to the surface in contact with the support being formed in an uneven shape. You may be comprised with a laminated body. Although there is no restriction | limiting in particular in the thickness of the film 8, When it is too thin, handling will become difficult, and since a total light transmittance will become low when it is too thick, 20 micrometers or more and 1000 micrometers or less are preferable.

<B1> Film Forming Method Next, the film 8 forming method will be described. The film 8 of this embodiment is obtained by forming an uneven shape on the surface of the film. The size of the concavo-convex shape formed on the surface is approximately the same as or larger than the wavelength of light, and is preferably 0.1 μm or more and 100 μm or less.

  When the film is made of an inorganic material such as glass, for example, a protective film in which a photoresist is cured is formed in advance on the base in a region where the uneven shape is not formed, and the unevenness is obtained by performing chemical etching or vapor phase etching. A surface can be formed. Moreover, when a film is comprised with a polymeric material, the following methods are illustrated as a method of forming an uneven surface on the film surface. For example, a method of transferring the uneven surface of the metal plate by pressing a metal plate with an uneven surface on a heated film, a method of rolling a polymer sheet or film using a roll with an uneven surface, an uneven shape A method of forming a film by extruding a polymer sheet from a slit having a surface, a method of forming a film by dropping a solution or dispersion containing a polymer material on a base having an uneven surface (hereinafter sometimes referred to as casting) After forming a film made of monomer, a method of selectively photopolymerizing a part of the film and removing the unpolymerized part, casting a polymer solution on a base under high humidity conditions, and forming a water droplet structure on the surface There is a method of forming a concavo-convex surface by a method of transferring to the surface.

  Among these methods, when a film is formed using a polymer material, there is a method in which a polymer solution is cast on a base and a water droplet structure is transferred to the surface under high humidity conditions for ease of production. Preferably used. This method is a known structure production method applying a dissipative process that is a kind of self-organization (see, for example, G. Widawski, M. Rawiso, B. Francois, Nature, p. 369-p. 387 (1994)). ).

<B1-1> Production of Film A method for producing a film using a method of forming a concavo-convex surface on a film surface by a method of casting a polymer solution on a base and transferring a water droplet structure to the surface will be described.
First, the above-described polymer material to be a film is dissolved in a solvent to prepare a film solution. Examples of the solvent include dichloromethane and chloroform. As a solution for a film, a high viscosity is preferable. Further, the solution for the film is preferably one having a high concentration of the polymer material to be a film, and the concentration of the polymer material to be a film is preferably 10 wt% or more. In order to improve the size and shape uniformity of the uneven shape, a small amount of a surfactant such as a nonionic surfactant may be added to the film solution.

  Next, the solution containing the material used as a film is apply | coated on one surface of the base used as the foundation | substrate on which the film is formed on the surface. Specifically, the prepared film solution is cast on one surface of a base under high humidity to form a liquid film composed of the film solution. Examples of the base include a support substrate made of the above-described polymer material and glass.

  Next, the solution applied on one surface of the base is kept in an atmosphere with a humidity of 80% or more and 90% or less, and then dried to form a film. When the liquid film is left under high humidity, water vapor in the atmosphere is liquefied and a plurality of droplets are formed on the surface of the liquid film. The droplets are substantially spherical and are discretely formed on the surface of the liquid film. The droplets formed on the surface of the liquid film increase in diameter over time due to further liquefaction of water vapor, and approximately half of the liquid droplets sink into the liquid film due to their own weight. Further, since the solvent in the liquid film evaporates with time, the shape of the droplet is transferred to the film during drying. The film thus formed has a plurality of concave surfaces on the surface, and is formed in an uneven shape. Specifically, a plurality of hemispherical depressions having a diameter of 1 μm or more and 100 μm or less are formed on the surface of the film. The film may be dried in a lower humidity atmosphere after a hemispherical depression is formed on the surface by holding the film in a range of 80% or more and 90% or less, and 80% or more. The film may be dried by holding the film in a range of 90% or less for a long time.

  When producing a film, the haze value of the produced film is controlled by controlling the application of the solution for the film so that the film thickness becomes a predetermined value and adjusting the humidity when the liquid film is dried. Can be controlled. Specifically, the film thickness of the liquid film at the start of drying is controlled so that the film thickness obtained by drying and film formation becomes a predetermined film thickness within a range of 100 μm or more and 200 μm or less. In addition, by controlling the humidity so that the predetermined humidity is within a range of 80% or more and 90% or less, a film having a haze value of 70% or more and showing an intended haze value is formed. Can do.

The haze value of the film can be controlled by controlling the humidity and the film thickness. When the humidity and the film thickness are changed, the surface of the liquid film changes depending on the concentration of the polymer material to be a film in the solution. This is because the time until drying changes, which changes the size of the concave and convex shape and the density of the concave surface to be formed, and the humidity has a great influence on the structure construction of the concave surface to be formed, such as improving the regularity of the concave surface arrangement. It is presumed that
The film thickness of the produced film can be controlled by adjusting the film thickness of the liquid film at the start of drying.
In addition, since the time until the surface of the liquid film is dried varies depending on the evaporation rate of the solvent and the boiling point of the solvent, the haze value of the film can be controlled by changing the solvent used.

  By such a method, a large-area film showing the intended optical characteristics can be easily produced with simple control and at low cost.

<B1-2> Installation of Film In the embodiment shown in FIG. 1, the film 8 is provided on the outer surface (second main surface 2 b) opposite to the transparent anode (first electrode) 3 side of the transparent support substrate 2. ing. The film 8 may be affixed on the outer surface (second main surface 2b) of the transparent support substrate 2 as described above. Alternatively, the transparent support substrate 2 may be used as a base, and the film may be directly formed on the outer surface (second main surface 2b) of the transparent support substrate 2.
Thereby, the film 8 is formed on the outer surface (second main surface 2b) of the transparent support substrate 2.

  In the organic EL element 1 of the present embodiment described above, the film 8 is disposed on the outermost layer on the light extraction side of the organic EL element, and the film 8 is formed with an uneven surface on the side opposite to the light emitting unit 4 side. Therefore, at least a part of the outer surface on the light extraction side of the organic EL element is formed in an uneven shape. For this reason, a part of the light generated by each of the light emitting layers 9a, 9b, and 9c in the light emitting unit 4 is incident on the film 8, diffracted on the uneven surface, and emitted to an atmosphere such as air, for example. . When the surface of the film 8 opposite to the light emitting portion 4 side is a flat surface, most of the light generated in each light emitting layer 9a, 9b, 9c of the light emitting portion 4 due to total reflection occurring on the surface of the organic EL element is taken outside. Not issued. On the other hand, by forming the surface on the side from which light is extracted in a concavo-convex shape, total reflection can be suppressed using the diffraction effect, and light can be extracted efficiently. In particular, since a film having a haze value of 70% or more and a total light transmittance of 80% or more is provided, the light extraction efficiency can be improved, and an organic EL element with high emission efficiency can be realized.

  In addition, since a plurality of concave surfaces are provided on the surface of the film 8 opposite to the light emitting portion 4 side, the concave surfaces exhibit a function similar to a concave lens. By providing such a film 8, the radiation angle of the light emitted from the organic EL element can be expanded.

  Further, the film 8 used in the organic EL element 1 of the present embodiment is formed by applying a solution containing the material to be the film 8 on one surface of a predetermined base and drying the applied liquid film. It is formed by doing. In particular, by applying a solution containing the material to be the film 8 so that the thickness of the film 8 after film formation is 100 μm or more and 200 μm or less, and further drying in a range where the humidity is 80% or more and 90% or less. Since the film 8 having an uneven surface, a haze value of 70% or more, and a total light transmittance of 80% or more can be produced, for example, by simple control of adjusting the application amount and humidity of the solution, Thus, the film 8 having optical characteristics can be easily manufactured.

  Further, as described above, since the film 8 used for the organic EL element can be easily produced by simple control, an organic EL element having high luminous efficiency can be easily produced.

  A top emission type in which a cathode (second electrode) 5 is formed on the surface of the substrate, and the cathode (second electrode) 5, the light emitting portion 4 and the transparent anode (first electrode) 3 are arranged in this order on the substrate. In the organic EL element, the film 8 is attached to the surface of the transparent anode (first electrode) 3 opposite to the light emitting portion 4 side.

  As described above, the organic EL element according to the present embodiment is characterized in that the light emitting portion disposed between the anode and the cathode has three or more light emitting layers, and each light emitting layer has light having different peak wavelengths. The light emitting layer having a longer peak wavelength of emitted light is disposed closer to the anode, and a film is provided on the surface of the transparent support substrate opposite to the light emitting portion. The details of these light emitting portions and films are as described above.

  Therefore, according to the organic EL element of the present embodiment described above, it is possible to realize an organic EL element with little change in color with respect to change in voltage applied to the electrode and high luminous efficiency. Therefore, the organic EL element of this embodiment can be suitably used as a display device such as a lighting device, a planar light source as a backlight, and a flat panel display.

Moreover, the organic EL element 1 according to the present embodiment includes a plurality of processes including the following steps (a) and (b), for example, using the method for producing the light emitting section 4 and the method for forming the film 8 as described above. It can manufacture with the manufacturing method of the organic EL element which has a light emission part containing the light emitting layer.
(A) Step of producing the light emitting part (b) Forming a film on the outermost layer on the first electrode side, which is one of an anode and a cathode based on the light emitting part and has light transmittance In the step (a) for producing the light emitting part, after applying the coating liquid containing the material constituting the light emitting layer, the coating liquid is then laminated on the surface of the light emitting layer formed by the coating liquid. A light emitting layer that is insolubilized in a coating solution containing a material constituting the light emitting layer and emits light having a short peak wavelength from the light emitting layer that emits light having a long peak wavelength from the anode toward the cathode. Each light emitting layer is sequentially formed so as to be sequentially arranged.
In the film forming step (b), according to the above-mentioned method of “preparing a film”, a solution containing a material to be a film is applied on one surface of a base serving as a base on which the film is formed on the surface, The solution applied on one surface of the base is kept in an atmosphere with a humidity of 80% or more and 90% or less, and then dried to form a film.

  Subsequently, components of the organic EL element other than the light emitting unit 4 and the film 8 will be described in detail below.

<C> Transparent Support Substrate The transparent support substrate 2 may be any substrate that does not change in the process of forming an organic EL element, that is, any substrate that does not change when an electrode is formed and an organic layer is formed. A flexible substrate may be used. For example, a glass plate, a plastic plate, a polymer film and a silicon plate, and a laminated plate obtained by laminating them are preferably used. Further, a plastic, a polymer film or the like that has been subjected to a low water permeability treatment can also be used. A commercially available substrate can be used as the transparent support substrate 2. Moreover, the transparent support substrate 2 can also be manufactured by a well-known method.

In the so-called bottom emission type organic EL element that takes out light from the light emitting portion 4 as shown in FIG. 1 from the transparent support substrate 2 side, the transparent support substrate 2 preferably has a high light transmittance in the visible light region. Used.
In the top emission type organic EL element that takes out light from the light emitting section 4 from the cathode 5 side as shown in a second embodiment to be described later, the support substrate may be transparent or opaque.

<D> 1st electrode A 1st electrode is an electrode of any one of an anode and a cathode, and is an electrode which has a light transmittance. The first electrode (anode in the configuration of FIG. 1) 3 in the present embodiment is a transparent electrode having light transmissivity that transmits light from each of the light emitting layers 9a, 9b, and 9c of the light emitting unit 4, and is usually a main electrode. It becomes an anode of the organic EL element of the invention. Further, as will be described later, an organic EL element having a configuration in which a light-transmitting first electrode is used as a cathode is also possible. As the transparent anode (first electrode) 3, a metal oxide, metal sulfide or metal thin film having high electrical conductivity can be used, and a material having high transmittance can be suitably used. It can be appropriately selected and used according to the above.

  Examples of the material of the transparent anode (first electrode) 3 include indium oxide, zinc oxide, tin oxide, ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), gold, A thin film of platinum, silver, copper or the like is used. Among these, ITO, IZO, and tin oxide are preferable.

  Further, as a constituent material of the transparent anode (first electrode) 3, an organic transparent conductive film such as polyaniline or a derivative thereof, polythiophene or a derivative thereof may be used.

  Further, from the viewpoint of facilitating charge injection into the light emitting layers 9a, 9b, 9c of the light emitting part 4, on the surface of the transparent anode (first electrode) 3 on the light emitting part 4 side, phthalocyanine derivatives, polythiophene derivatives, etc. One or more layers of conductive polymer, Mo oxide, amorphous carbon, carbon fluoride, polyamine compound, etc., and 200 nm or less, or layers having an average film thickness of 10 nm or less made of metal oxide, metal fluoride, organic insulating material, etc. May be provided.

  The film thickness of such a transparent anode (first electrode) 3 can be appropriately selected in consideration of light transmittance and electrical conductivity, and is, for example, 5 nm or more and 10 μm or less, preferably 10 nm or more, 1 μm or less, more preferably 20 nm or more and 500 nm or less.

Examples of the method for forming the transparent anode (first electrode) 3 include a vacuum deposition method, a sputtering method, an ion plating method, and a plating method.
Examples of the method of partitioning the transparent anode (first electrode) 3 into a plurality of electrically separated cells include a method of forming a pattern by an etching method using a photoresist after forming the first electrode. .

<E> Second electrode The second electrode is disposed opposite the first electrode and is the other of the anode and the cathode. The 2nd electrode 5 in this embodiment is an electrode arrange | positioned facing the transparent anode (1st electrode) 3, Comprising: It becomes a cathode of an organic EL element. As such a cathode material, a material having a small work function and easy electron injection into the light emitting layer is preferable. The cathode material is preferably a material having high electrical conductivity and high visible light reflectance. Specific examples of such cathode materials include metals, metal oxides, alloys, graphite or graphite intercalation compounds, and inorganic semiconductors such as zinc oxide (ZnO). An organic EL element having a configuration using the second electrode as an anode is also possible.

  As the metal, an alkali metal, an alkaline earth metal, a transition metal, a group 13 metal of the periodic table, or the like can be used. Specific examples of these metals include lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, gold, silver, platinum, copper, manganese, titanium, cobalt, nickel, tungsten, tin, and aluminum. , Scandium, vanadium, zinc, yttrium, indium, cerium, samarium, europium, terbium, ytterbium, and the like.

  Examples of the alloy include alloys containing at least one of the above metals. Specifically, magnesium-silver alloy, magnesium-indium alloy, magnesium-aluminum alloy, indium-silver alloy, lithium-aluminum alloy, lithium -A magnesium alloy, a lithium-indium alloy, a calcium-aluminum alloy, etc. can be mentioned.

  The cathode (second electrode) 5 is an electrode having optical transparency as necessary, for example, when light is taken out from the cathode side. Examples of such a light-transmitting cathode material include conductive oxides such as indium oxide, zinc oxide, tin oxide, ITO, and IZO; and conductive organic substances such as polyaniline or a derivative thereof, polythiophene or a derivative thereof. Can do.

  The cathode (second electrode) 5 may have a laminated structure of two or more layers. In some cases, the electron injection layer is used as a cathode.

  The film thickness of the cathode (second electrode) 5 can be appropriately selected in consideration of electrical conductivity and durability, but is, for example, 10 nm or more and 10 μm or less, preferably 20 nm or more and 1 μm or less, More preferably, it is 50 nm or more and 500 nm or less.

  Examples of the method for forming the cathode (second electrode) 5 include a vacuum deposition method, a sputtering method, and a laminating method in which a metal thin film is thermocompression bonded.

<F> Protective Film After the cathode (second electrode) 5 is formed as described above, it has a transparent anode (first electrode) 3-a light emitting part 4-cathode (second electrode) 5 as a basic structure. In order to protect the light emitting function part 6, a protective film (upper sealing film) 7 for sealing the light emitting function part 6 is formed. This protective film 7 usually has at least one inorganic layer and at least one organic layer. The number of stacked layers is determined as necessary. Basically, inorganic layers and organic layers are alternately stacked.

  Moreover, the shape of the protective film 7 should just be what can be bonded together with the transparent support substrate 2, and can seal the light emission function part 6, may be flat form as shown in FIG. 1, and may be a box-shaped board | substrate May be used (not shown). In the example shown in FIG. 1, no gap is generated between the protective film 7 and the light emitting function unit 6, but when there is a gap between the protective film 7 and the light emitting function unit 6, A filler such as a resin may be provided. The protective film 7 may be the same as the example illustrated for the transparent support substrate 2.

  The plastic substrate has a higher gas and liquid permeability than the glass substrate, and the light emitting material such as the light emitting layer constituting the light emitting portion 4 is easily oxidized and easily deteriorated by contact with water. In the case where a plastic substrate is used as the substrate 2, even if the light emitting function unit 6 is encapsulated by the transparent support substrate 2 and the protective film 7, it is likely to change with time. It is preferable to apply. For example, it is preferable to stack a lower sealing film having a high barrier property against gas and liquid on a plastic substrate, and then stack the light emitting function part 6 on the lower sealing film. This lower sealing film is usually formed with the same configuration and the same material as the protective film (upper sealing film) 7.

<Modification>
As mentioned above, although the structure of the organic EL element of this embodiment was demonstrated, the modification of the structure of the organic EL element of this embodiment is demonstrated below.

<G> Layer provided between anode and light emitting part In the present embodiment, a hole injection layer and a hole transport layer are provided between the transparent anode (first electrode) 3 and the light emitting part 4 as necessary. An electronic block layer or the like is provided.

  The hole injection layer is a layer having a function of improving the efficiency of hole injection from the transparent anode (first electrode) 3. The hole transport layer is a layer having a function of improving hole injection from the transparent anode (first electrode) 3, the hole injection layer or the hole transport layer closer to the transparent anode (first electrode) 3. The electron blocking layer is a layer having a function of blocking electron transport. When the hole injection layer and / or the hole transport layer has a function of blocking electron transport, these layers may also serve as an electron blocking layer. The fact that the electron blocking layer has a function of blocking electron transport makes it possible, for example, to produce an element that allows only electron current to flow and confirm the blocking effect by reducing the current value.

<G1> Hole Injection Layer As described above, the hole injection layer is formed between the transparent anode (first electrode) 3 and the hole transport layer, or between the transparent anode (first electrode) 3 and the light emitting unit 4. It can be provided in between. As a material constituting the hole injection layer, a known material can be appropriately used, and there is no particular limitation. For example, phenylamine, starburst amine, phthalocyanine, hydrazone derivative, carbazole derivative, triazole derivative, imidazole derivative, oxadiazole derivative having amino group, vanadium oxide, tantalum oxide, tungsten oxide, molybdenum oxide, ruthenium oxide And oxides such as aluminum oxide, amorphous carbon, polyaniline, polythiophene derivatives, and the like.

  As a method for forming the hole injection layer, it can be formed by a method similar to the method for forming the light emitting layer constituting the light emitting portion 4 described above. Specifically, the above-mentioned light emitting layer is formed by applying a coating solution in which a material that becomes a hole injection layer (hole injection material) is dissolved in a solvent similar to the solvent for dissolving the light emitting material mainly constituting the light emitting layer. It can form into a film by apply | coating with the application | coating method used when doing.

  The thickness of the hole injection layer is preferably about 5 nm to 300 nm. If the thickness is less than 5 nm, the production tends to be difficult. On the other hand, if the thickness exceeds 300 nm, the driving voltage and the voltage applied to the hole injection layer tend to increase.

<G2> Hole transport layer The material constituting the hole transport layer is not particularly limited. For example, N, N'-diphenyl-N, N'-di (3-methylphenyl) 4,4'- Aromatic amine derivatives such as diaminobiphenyl (TPD), 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPB), polyvinylcarbazole or derivatives thereof, polysilane or derivatives thereof, side chain Or a polysiloxane derivative having an aromatic amine in the main chain, pyrazoline derivative, arylamine derivative, stilbene derivative, triphenyldiamine derivative, polyaniline or derivative thereof, polythiophene or derivative thereof, polyarylamine or derivative thereof, polypyrrole or derivative thereof, Poly (p-phenylene vinylene) or Derivative or a poly (2,5-thienylene vinylene) or derivatives thereof is illustrated.

  Among these, as the hole transport material used for the hole transport layer, polyvinyl carbazole or a derivative thereof, polysilane or a derivative thereof, a polysiloxane derivative having an aromatic amine compound group in a side chain or a main chain, polyaniline or a derivative thereof, Polymeric hole transport materials such as polythiophene or derivatives thereof, polyarylamine or derivatives thereof, poly (p-phenylene vinylene) or derivatives thereof, or poly (2,5-thienylene vinylene) or derivatives thereof are preferred, and more preferred Is polyvinyl carbazole or a derivative thereof, polysilane or a derivative thereof, and a polysiloxane derivative having an aromatic amine in the side chain or main chain. In the case of a low-molecular hole transport material, it is preferably used by being dispersed in a polymer binder.

  The method for forming the hole transport layer is not particularly limited, but in the case of a low molecular hole transport material, film formation from a mixed solution containing a polymer binder and a hole transport material can be exemplified. Examples of molecular hole transport materials include film formation from a solution containing a hole transport material.

The solvent used for film formation from a solution is not particularly limited as long as it can dissolve a hole transport material. Chlorine solvents such as chloroform, methylene chloride, dichloroethane, ether solvents such as tetrahydrofuran, toluene, xylene And aromatic hydrocarbon solvents such as acetone, ketone solvents such as acetone and methyl ethyl ketone, and ester solvents such as ethyl acetate, butyl acetate, and ethyl cellosolve acetate.
Examples of the film forming method from a solution include the same coating method as the above-described film forming method of the hole injection layer.

  As the polymer binder to be mixed, those that do not extremely inhibit charge transport are preferable, and those that weakly absorb visible light are preferably used. For example, polycarbonate, polyacrylate, polymethyl acrylate, polymethyl methacrylate, polystyrene, poly Examples thereof include vinyl chloride and polysiloxane.

  The thickness of the hole transport layer is not particularly limited, but can be appropriately changed according to the intended design, and is preferably about 1 nm or more and 1000 nm or less. When this thickness is less than the lower limit, production becomes difficult. Or, there is a tendency that the effect of hole transport is not sufficiently obtained. On the other hand, when the upper limit is exceeded, the driving voltage and the voltage applied to the hole transport layer tend to increase. Therefore, as described above, the thickness of the hole transport layer is preferably 1 nm or more and 1000 nm or less, more preferably 2 nm or more and 500 nm or less, and further preferably 5 nm or more and 200 nm or less. .

<H> Layer provided between the cathode and the light-emitting portion Between the light-emitting portion 4 and the cathode (second electrode) 5, an electron injection layer, an electron transport layer, a hole blocking layer, etc. are provided as necessary. Provided.

In the case where only one layer is provided between the cathode (second electrode) 5 and the light emitting portion 4, the layer is referred to as an electron injection layer. When both the electron injection layer and the electron transport layer are provided between the cathode (second electrode) 5 and the light emitting portion 4, the layer in contact with the cathode (second electrode) 5 is called an electron injection layer. The layer excluding the electron injection layer is referred to as an electron transport layer.
The electron injection layer is a layer having a function of improving the efficiency of electron injection from the cathode (second electrode). The electron transport layer is a layer having a function of improving electron injection from an electron transport layer closer to the cathode (second electrode), the electron injection layer, or the cathode (second electrode). The hole blocking layer is a layer having a function of blocking hole transport. In the case where the electron injection layer and / or the electron transport layer have a function of blocking hole transport, these layers may also serve as the hole blocking layer. The fact that the hole blocking layer has a function of blocking hole transport makes it possible, for example, to produce an element that allows only a hole current to flow, and confirm the blocking effect by reducing the current value.

<H1> Electron Injection Layer As described above, the electron injection layer is provided between the electron transport layer and the cathode or between the light emitting unit 4 and the cathode (second electrode) 5. Depending on the type of the light emitting layer, the electron injection layer may be an alkali metal or alkaline earth metal, an alloy containing one or more of the above metals, an oxide, halide and carbonate of the metal, or a mixture of the substances. Etc.

  Examples of alkali metals or oxides, halides and carbonates thereof include lithium, sodium, potassium, rubidium, cesium, lithium oxide, lithium fluoride, sodium oxide, sodium fluoride, potassium oxide, potassium fluoride, rubidium oxide. , Rubidium fluoride, cesium oxide, cesium fluoride, lithium carbonate and the like.

  Examples of the alkaline earth metals or oxides, halides and carbonates thereof include magnesium, calcium, barium, strontium, magnesium oxide, magnesium fluoride, calcium oxide, calcium fluoride, calcium fluoride, barium oxide, fluorine. Barium fluoride, strontium oxide, strontium fluoride, magnesium carbonate and the like.

  Furthermore, a metal, a metal oxide, an organometallic compound doped with a metal salt, an organometallic complex compound, or a mixture thereof can also be used as a material for the electron injection layer.

This electron injection layer may have a stacked structure in which two or more layers are stacked. Specifically, Li / Ca etc. are mentioned. This electron injection layer is formed by vapor deposition, sputtering, printing, or the like.
The thickness of the electron injection layer is preferably about 1 nm or more and 1 μm or less.

<H2> Electron Transport Layer As materials for forming the electron transport layer, known materials can be used, such as oxadiazole derivatives, anthraquinodimethane or derivatives thereof, benzoquinones or derivatives thereof, naphthoquinones or derivatives thereof, anthraquinones or derivatives thereof. , Tetracyanoanthraquinodimethane or derivatives thereof, fluorenone derivatives, diphenyldicyanoethylene or derivatives thereof, diphenoquinone derivatives, or metal complexes of 8-hydroxyquinoline or derivatives thereof, polyquinoline or derivatives thereof, polyquinoxaline or derivatives thereof, polyfluorene or derivatives thereof Examples thereof include derivatives thereof.

  Of these, oxadiazole derivatives, benzoquinone or derivatives thereof, anthraquinones or derivatives thereof, or metal complexes of 8-hydroxyquinoline or derivatives thereof, polyquinoline or derivatives thereof, polyquinoxaline or derivatives thereof, polyfluorene or derivatives thereof are preferred, 2- (4-biphenylyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole, benzoquinone, anthraquinone, tris (8-quinolinol) aluminum, and polyquinoline are more preferable.

Although there is no restriction | limiting in particular as the film-forming method of an electron carrying layer, In the low molecular electron transport material, the vacuum evaporation method from powder or the method by the film-forming from a solution or a molten state etc. are illustrated. Examples of the polymer electron transport material include a method of film formation from a solution or a molten state.
Further, when forming a film from a solution or a molten state, a polymer binder may be used in combination.
Examples of the method for forming the electron transport layer from the solution include the same film formation method as the method for forming the hole injection layer from the above-described solution.

  The film thickness of the electron transport layer varies depending on the material used, and is selected so that the driving voltage and the light emission efficiency are appropriate values. At least a thickness that does not cause pinholes is required. Too much is not preferable because the driving voltage of the element increases. Therefore, the thickness of the electron transport layer is, for example, 1 nm or more and 1 μm or less, preferably 2 nm or more and 500 nm or less, and more preferably 5 nm or more and 200 nm or less.

  The electron injection layer and the hole injection layer may be collectively referred to as a charge injection layer, and the electron transport layer and the hole transport layer may be collectively referred to as a charge transport layer.

<I> Combination of layer configurations of light emitting functional unit including anode, cathode, and light emitting unit Combination of layer configurations from transparent anode (first electrode) 3 to cathode (second electrode) 5 in the organic EL element of the present embodiment An example is shown below.
a) Anode / light emitting part / cathode b) Anode / hole injection layer / light emitting part / cathode c) Anode / light emitting part / electron injection layer / cathode d) Anode / hole injection layer / light emitting part / electron injection layer / cathode e) Anode / hole injection layer / hole transport layer / light emitting portion / cathode f) Anode / light emitting portion / electron transport layer / electron injection layer / cathode g) Anode / hole injection layer / light emitting portion / electron transport layer / Electron injection layer / cathode h) anode / hole injection layer / hole transport layer / light emitting part / electron injection layer / cathode i) anode / hole injection layer / hole transport layer / light emitting part / electron transport layer / electron injection Layer / Cathode (Here, the symbol “/” indicates that the layers sandwiching the symbol “/” are adjacently stacked. The same applies hereinafter.)

In the embodiment shown in FIG. 1 and the like, a set of light emitting units 4 is provided. However, as a modification thereof, it is possible to adopt a form in which two or more sets of light emitting portions are provided in an overlapping manner. Here, in any one of the layer configurations of (a) to (i) above, when the layered body sandwiched between the anode and the cathode is “repeating unit A”, for example, the following (j) The layer structure shown can also be employed.
j) Anode / (repeat unit A) / charge generation layer / (repeat unit A) / cathode

As an organic EL device having three or more light emitting layers, when “(repeating unit A) / charge injection layer” is “repeating unit B”, for example, the layer configuration shown in the following (k) can be exemplified. .
k) Anode / (Repeating unit B) _n / (Repeating unit A) / Cathode

The symbol “n” represents an integer of 2 or more. (Repeating unit B) _n represents a laminate in which n layers of repeating units B are laminated.
In the layer configurations j) and k), layers other than the anode, electrode, cathode, and light emitting layer may be omitted as necessary.

  The charge generation layer is a layer that generates holes and electrons by applying an electric field. Examples of the charge generation layer include a thin film made of vanadium oxide, ITO, molybdenum oxide, or the like.

  In an organic EL element, an anode is usually disposed on the substrate side, but a cathode may be disposed on the substrate side.

In the above configuration, among the layers provided adjacent to the electrode, those having the function of improving the charge injection efficiency from the electrode and having the effect of lowering the driving voltage of the element are particularly charge injection layers (hole injection layers). , Sometimes referred to as an electron injection layer).
Two or more hole transport layers and electron transport layers may be used independently.

  In the organic EL device of this embodiment, an insulating layer having a thickness of 2 nm or less may be provided adjacent to the electrode in order to further improve the adhesion with the electrode or improve the charge injection property from the electrode. In addition, a thin buffer layer may be inserted between each of the aforementioned layers in order to improve adhesion at the interface or prevent mixing.

[Second Embodiment]
Next, a second embodiment of the organic EL element according to the present invention will be described with reference to FIG. FIG. 2 is a front cross-sectional view showing a second embodiment of the organic EL element of the present invention.
The difference between the second embodiment and the first embodiment described above is that the organic EL element of the first embodiment has a transparent anode (first electrode) 3 having a light-transmitting property from the light emitting unit 4. Whereas the organic EL element 11 of the second embodiment transmits light from the light emitting portion 12 while transmitting the light from the transparent support substrate 2 that transmits light and emits the light to the outside. This is a top emission type element that is transmitted through a transparent cathode (first electrode) 13 having a light transmission and exits from a light-transmitting protective film 14.

  In the second embodiment, the first electrode having the light transmission property that transmits light from the light emitting unit 12 is the transparent cathode 12, and the transparent cathode (first electrode) 13 on the opposite side to the light emitting unit 12. A protective film 14 is formed on the surface. A film 15 is provided on the surface of the protective film 14 opposite to the light emitting part 12 side, and the film 15 corresponds to the outermost layer on the transparent cathode (first electrode) 13 side with respect to the light emitting part 12. To do. That is, a protective film 14 having a first main surface 14a and a second main surface 14b is interposed between the transparent cathode (first electrode) 13 and the film 15, and the transparent cathode (first electrode) 13, the light emitting unit 12, and The light emitting function part 17 including the cathode (second electrode) 16 is mounted on the support substrate 18 in the order of the transparent cathode (first electrode) 13, the light emitting part 12, and the cathode (second electrode) 16 from the vicinity of the first main surface 14a. The film 15 is provided in contact with the second main surface 14b.

  For the transparent cathode (first electrode) 13 in the present embodiment, for example, a metal thin film exemplified as the cathode in the first embodiment can be used as the transparent cathode. Since the metal thin film used for the transparent cathode (first electrode) 13 is formed into a thin film to the extent that light can be transmitted, the sheet resistance is increased. Therefore, the transparent cathode (first electrode) 13 is preferably constituted by a laminate in which a transparent anode such as an ITO thin film is laminated in a metal thin film shape. In addition, it is preferable to provide a reflective film having a high reflectance such as silver between the anode (second electrode) 16 and the support substrate 18, and by providing such a reflective film, light directed toward the support substrate 18 side. Can be reflected to the transparent cathode (first electrode) 13 side, and the light extraction efficiency can be improved.

  The film 15 in the second embodiment is made of the same member as the film 8 in the first embodiment, and is provided in contact with the outer surface (second main surface 14b) of the protective film 14. The concavo-convex surface is provided on the surface opposite to the light emitting unit 12 side. In this case, the protective film 14 is preferably a sealing substrate.

  Moreover, the uneven | corrugated shape of the film 15, thickness dimension, various characteristics, such as a haze value, a total light transmittance, and the preparation method are the same as that of the film 8 in 1st Embodiment. That is, the surface of the film 15 on the light emitting unit 12 side is flat, and the surface on the side opposite to the light emitting unit 12 side is formed in an uneven shape. The film 15 has a haze value of 70% or more and a total light transmittance of 80% or more. The size (width) of the convex or concave surface in the width direction perpendicular to the thickness direction of the film 15 is preferably 0.5 μm or more and 20 μm or less, and more preferably 1 μm or more and 2 μm or less. The height of the convex surface or concave surface in the thickness direction of the film 15 is preferably 0.25 μm or more and 10 μm or less, more preferably 0.5 μm or more and 1.0 μm or less. The shape of the convex or concave surface of the film 15 is not particularly limited, but is preferably a curved surface, more preferably a hemispherical shape. The concave surface or convex surface of the film 15 is preferably arranged regularly.

  In the second embodiment, the light emitting unit 12 disposed between the anode (second electrode) 16 and the transparent cathode (first electrode) 13 is the same as the light emitting unit 4 in the first embodiment described above. It's okay. That is, the light emitting unit 12 has three or more light emitting layers. The light emitting layer included in the light emitting unit 12 preferably has a red light emitting layer 19a, a green light emitting layer 19b, and a blue light emitting layer from the anode (second electrode) 16 toward the transparent cathode (first electrode) 13. 19c are stacked in this order.

Even if the organic EL device according to the present invention is configured as in the second embodiment, the same actions and effects as those in the first embodiment can be obtained.
In other words, the organic EL element of the present invention has little change in color with respect to the change in voltage applied to the electrodes and can increase the light emission efficiency in both the first embodiment and the second embodiment. As still another embodiment, the protective film 14 may be removed from the components of the second embodiment, and the film 15 may be provided in contact with the transparent cathode (first electrode) 13. In this case, by configuring the film 15 with a member having a high barrier property against air, water vapor, and the like, the film 15 can function as a protective film, and the configuration of the organic EL element can be simplified.

<Apparatus equipped with organic EL element of the present invention>
The organic EL element of each embodiment of the present invention described above can be suitably used for a curved or flat illumination device, for example, a planar light source used as a light source of a scanner, or a display device.

  Examples of the display device including the organic EL element include an active matrix display device, a passive matrix display device, a segment display device, a dot matrix display device, and a liquid crystal display device. The organic EL element is used as a light emitting element constituting each pixel in an active matrix display device and a passive matrix display device, and is used as a light emitting element constituting each segment in a segment display device, and emits light in a dot matrix display device. Used as an element or a backlight, and used as a backlight in a liquid crystal display device.

  The organic EL element according to the embodiment of the present invention has a change width between the coordinate value x and the coordinate value y in the chromaticity coordinates of the extracted light when the voltage applied between the anode and the cathode is changed. However, it is possible to make each 0.05 or less, and there is little change in color, and it is suitably used for the above-described planar light source, illumination device, and display device. In particular, as the lighting device, it is preferable that the color does not change when the brightness is adjusted by changing the voltage applied between the anode and the cathode, and the coordinates in the chromaticity coordinates of the light from the lighting device are preferable. Since the change width between the value x and the coordinate value y is preferably 0.05 or less, the organic EL element of the present invention is suitably used for a lighting device.

  Similarly, as the backlight of the dot matrix display device and the liquid crystal display device, it is preferable that the color does not change when the brightness is adjusted, the coordinate value x in the chromaticity coordinates of the light from the backlight, Since the range of change from the coordinate value y is preferably 0.05 or less, the organic EL element of the present invention is also suitably used for a backlight.

  Moreover, since the organic EL element of embodiment of this invention is provided with the hollow which exhibits the function similar to a concave lens on the surface of the films 8 and 15 as mentioned above, it can implement | achieve illumination with a wide radiation angle. it can.

  Hereinafter, although the present invention will be described in more detail based on production examples and comparative examples, the present invention is not limited to the following production examples.

<Production Example 1> Production of Organic EL Element Having Light-Emitting Section In this Production Example 1, light transmission is performed in order to confirm the effect of arranging a plurality of light-emitting layers having different peak wavelengths of emitted light in a predetermined order. A transparent anode, which is a first electrode having optical transparency, is disposed on a transparent support substrate having a property, and emits light to the hole injection layer, red, green, and blue on the transparent anode (first electrode). The light-emitting part is composed of three light-emitting layers, arranged in the order of the red light-emitting layer, the green light-emitting layer, and the blue light-emitting layer from the transparent anode (first electrode) side, and the cathode that is the second electrode is disposed thereon. An organic EL element was manufactured, and the improvement of the light emission characteristics was confirmed.

An organic EL element having a light emitting portion was produced as follows. A glass substrate was used as the transparent supporting substrate having light transmittance, and an ITO film formed on the glass substrate by a sputtering method and patterned into a predetermined shape was used as a transparent anode (first electrode). A transparent anode having a thickness of 150 nm was used. The transparent support substrate on which the transparent anode is formed is washed with an alkaline detergent and ultrapure water, dried, and then UV-O ₃ apparatus (trade name “Model 312 UV-O ₃ Cleaning System” manufactured by Technovision Co., Ltd.) ) Was used for UV-O ₃ treatment.

  Next, a suspension of poly (3,4) ethylenedioxythiophene / polystyrene sulfonic acid (trade name “BaytronP TP AI4083” manufactured by HC Starck Vitec Co., Ltd.) was filtered through a membrane filter having a pore size of 0.2 μm. . A thin film was formed on the transparent anode by spin-coating the liquid obtained by filtration. Next, the hot plate was heated at 200 ° C. for 10 minutes to obtain a hole injection layer having a thickness of 70 nm.

  Next, a red light emitting layer was laminated on the hole injection layer. First, xylene is used as a solvent, a light emitting material (manufactured by SUMION, trade name “PR158”) is used as a material mainly constituting the red light emitting layer, and dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku, A coating solution was prepared using a trade name “KAYARAD DPHA”). The weight ratio of the light emitting material to the cross-linking agent was 4: 1, and the ratio of the combined material of the light emitting material and the cross-linking agent in the coating solution was 1.0% by mass. The coating solution thus obtained was spin-coated to form a thin film on the hole injection layer. Next, it heated at 200 degreeC for 20 minute (s) in nitrogen atmosphere, and obtained the red light emitting layer with a film thickness of 10 nm. By performing such a heat treatment, the thin film was dried to remove the solvent, and the crosslinking agent was crosslinked to insolubilize the red light emitting layer in the coating solution to be applied next.

  Next, the green light emitting layer was laminated | stacked on the red light emitting layer. First, xylene is used as a solvent, a light emitting material (manufactured by SUMATION, product name “Green 1300”) is used as a material mainly constituting the green light emitting layer, and dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku, A coating solution was prepared using a trade name “KAYARAD DPHA”). The weight ratio of the light emitting material to the cross-linking agent was 4: 1, and the ratio of the combined material of the light emitting material and the cross-linking agent in the coating solution was 1.0% by mass. A thin film was formed on the red light emitting layer by spin coating the coating solution thus obtained. Next, it heated at 200 degreeC for 20 minute (s) in nitrogen atmosphere, and obtained the green light emitting layer with a film thickness of 15 nm. By performing such heat treatment, the thin film was dried to remove the solvent, and the cross-linking agent was cross-linked to insolubilize the green light-emitting layer in the coating solution to be applied next.

  Next, a blue light emitting layer was laminated on the green light emitting layer. First, xylene was used as a solvent, and a coating liquid was prepared using a light emitting material (manufactured by SUMION, trade name “BP361”) as a material mainly constituting the blue light emitting layer. The ratio of the blue light emitting material in the coating solution was 1.5% by mass. The coating solution thus obtained was spin-coated to form a thin film on the green light emitting layer. Next, it heated at 130 degreeC for 20 minute (s) in nitrogen atmosphere, and obtained the blue light emitting layer with a film thickness of 55 nm. In addition, the shape of the cross section cut by the plane perpendicular to the thickness direction of each light emitting layer was a square of 2 mm × 2 mm.

Next, the substrate on which the blue light emitting layer is formed as described above is introduced into a vacuum vapor deposition machine, and barium is deposited on the blue light emitting layer to form a thin film made of barium having a thickness of about 5 nm. Further, aluminum is vapor-deposited on the thin film made of barium to form a thin film made of aluminum having a thickness of about 80 nm, and a cathode composed of a laminate of the thin film made of barium and the thin film made of aluminum is formed. did. When the degree of vacuum reached 5 × 10 ⁻⁵ Pa or less, vapor deposition of barium and aluminum was started.

<Comparative Example 1> Production of Organic EL Element As Comparative Example 1, an organic EL element having a light emitting portion composed of only a single light emitting layer (hereinafter sometimes referred to as a white light emitting layer) emitting light in a white wavelength region was produced. . Since the manufacturing process other than the white light emitting layer is the same as the manufacturing process of the organic EL element of Production Example 1, a duplicate description is omitted and only the manufacturing process of the white light emitting layer will be described.

  First, xylene was used as a solvent, and a coating solution was prepared using a light emitting material (manufactured by SUMION, trade name “WP1330”) as a material mainly constituting the white light emitting layer. The ratio of the luminescent material in the coating solution was 1.0% by mass. The thin film was formed on the positive hole injection layer by spin-coating the coating liquid obtained in this way on the board | substrate with which the positive hole injection layer was formed. Next, it heated at 130 degreeC for 20 minute (s) in nitrogen atmosphere, and obtained the white light emitting layer with a film thickness of 80 nm.

Comparative Example 2 Production of Organic EL Element As Comparative Example 2, an organic EL element that differs from the organic EL element of Production Example 1 only in the stacking order of the three layers of the red light emitting layer, the green light emitting layer, and the blue light emitting layer. Produced. A blue light emitting layer was disposed in the layer closest to the anode, a green light emitting layer was disposed in the middle layer, and a red light emitting layer was disposed in the layer closest to the cathode. Since the manufacturing processes other than the red light emitting layer, the green light emitting layer, and the blue light emitting layer are the same as the manufacturing process of the organic EL element of Preparation Example 1, only the manufacturing process of the red light emitting layer, the green light emitting layer, and the blue light emitting layer will be described. To do.

  First, a blue light emitting layer was laminated on the hole injection layer. Xylene is used as a solvent for the coating solution, a light emitting material (manufactured by SUMION, trade name “BP361”) is used as a material mainly constituting the blue light emitting layer, and dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku Co., Ltd.) is used as a crosslinking agent. , Trade name “KAYARAD DPHA”). The weight ratio of the light emitting material to the cross-linking agent was 4: 1, and the ratio of the combined material of the light emitting material and the cross-linking agent in the coating solution was 1.0% by mass. The coating solution thus obtained was spin-coated to form a thin film on the hole injection layer. Next, it heated at 130 degreeC for 20 minute (s) in nitrogen atmosphere, and obtained the blue light emitting layer with a film thickness of 55 nm. By performing such heat treatment, the thin film was dried to remove the solvent, and the crosslinking agent was crosslinked to insolubilize the blue light-emitting layer in the coating solution to be applied next.

  Next, the green light emitting layer was laminated on the blue light emitting layer. First, xylene is used as a solvent, a light emitting material (manufactured by SUMATION, product name “Green 1300”) is used as a material mainly constituting the green light emitting layer, and dipentaerythritol hexaacrylate (manufactured by Nippon Kayaku, A coating solution was prepared using a trade name “KAYARAD DPHA”). The weight ratio of the light emitting material to the cross-linking agent was 4: 1, and the ratio of the combined material of the light emitting material and the cross-linking agent in the coating solution was 1.0% by mass. A thin film was formed on the blue light emitting layer by spin coating the coating solution thus obtained. Next, it heated at 200 degreeC for 20 minute (s) in nitrogen atmosphere, and obtained the green light emitting layer with a film thickness of 15 nm. By performing such heat treatment, the thin film was dried to remove the solvent, and the cross-linking agent was cross-linked to insolubilize the green light-emitting layer in the coating solution to be applied next.

  Next, the red light emitting layer was laminated on the green light emitting layer. First, xylene was used as a solvent, and a coating solution was prepared using a light emitting material (manufactured by SUMATION, trade name “PR158”) as a material mainly constituting the red light emitting layer. The ratio of the luminescent material in the coating solution was 1.0% by mass. The coating solution thus obtained was spin-coated to form a thin film on the green light emitting layer. Next, it heated at 200 degreeC for 20 minute (s) in nitrogen atmosphere, and obtained the red light emitting layer with a film thickness of 10 nm.

<Evaluation of effect by arrangement of a plurality of light emitting layers having different emission wavelengths in a predetermined order>
A voltage was applied to each organic EL element of Production Example 1, Comparative Example 1, and Comparative Example 2 to measure luminance and chromaticity. In the measurement, the applied voltage was changed stepwise, and the luminance and chromaticity were measured for each applied voltage. The measurement results are shown in Table 1.

Of changing the voltage applied when changing the luminance to ^{100cd / m 2 ~10000cd / m 2} , Preparation Example 1, Comparative Example 1, the coordinate value x in the CIE chromaticity coordinates of the organic EL device of Comparative Example 2, Table 2 shows the respective change widths of y.

As shown in Table 1 and Table 2, the organic EL device of Preparation Example 1, when the brightness by changing the voltage to be applied was changed from ^{100cd / m 2 ~10000cd / m 2} , the light extracted chromaticity The width of change of the coordinate value x and the coordinate value y in the coordinates was 0.016 or less, respectively.

As shown in Table 1, the organic EL device of Production Example 1 has a maximum current efficiency improved by providing three light emitting layers as compared with the organic EL device of Comparative Example 1 composed of only one light emitting layer. did.
In addition, the organic EL element of Production Example 1 was improved in the maximum value of current efficiency as compared with the organic EL element of Comparative Example 2 by arranging the three light emitting layers in a predetermined arrangement.

  Further, as shown in Table 1, the organic EL element of Preparation Example 1 is more resistant to changes in voltage than the organic EL element of Comparative Example 1 including only one light emitting layer by providing three light emitting layers. There was little change in taste. In addition, the organic EL element of Production Example 1 had less change in color with respect to voltage change than the organic EL element of Comparative Example 2 by arranging the three light emitting layers in a predetermined arrangement.

  In the following Production Examples 2 and 3 and Comparative Examples 3 to 5, it was confirmed that the light extraction efficiency can be controlled by providing a film on the outer surface of the transparent support substrate.

<Production Example 2> Production of organic EL device having film An organic EL device having a film was produced as follows. A 30 mm × 30 mm glass substrate was used as a transparent supporting substrate having light permeability. Next, a conductor film made of ITO having a thickness of 150 nm was deposited on the surface of the support substrate by sputtering. Next, a protective film having a predetermined pattern shape was formed by applying a photoresist on the surface of the conductor film, exposing a predetermined region through a photomask, and further washing the conductive film. After further etching, rinsing was performed with water and NMP (n-methylpyrrolidone) to form an anode made of an ITO film having a predetermined pattern shape. Next, in order to remove the resist residue on the anode, oxygen plasma treatment was performed for 2 minutes at an energy of 30 W, and UV / O ₃ cleaning was performed for 20 minutes.

  Next, a suspension of poly (3,4) ethylenedioxythiophene / polystyrene sulfonic acid (trade name: BaytronP CH8000, manufactured by Starck Vitec Co., Ltd.) is subjected to two-stage filtration to obtain a solution for a hole injection layer. Got. In the first stage filtration, a 0.45 μm diameter filter was used, and in the second stage filtration, a 0.2 μm diameter filter was used. A thin film is formed by spin coating using the solution obtained by filtration, and a hole injection layer having a thickness of 70 nm is formed by heat treatment at 200 ° C. for 15 minutes on a hot plate in an air atmosphere. did.

  Next, Lumination WP1330 (manufactured by SUMATION) and xylene were mixed to prepare a xylene solution. The concentration of Lumation WP1330 in the xylene solution was 1.2% by mass. Using the prepared solution, a thin film was formed on the surface of the hole injection layer by spin coating, and then heat-treated on a hot plate at 130 ° C. for 60 minutes in a nitrogen atmosphere to form a light-emitting layer having a thickness of 80 nm. did.

Next, the support substrate on which the light emitting layer was formed was introduced into a vacuum vapor deposition machine, and Ba and Al were sequentially deposited at a thickness of 5 nm and 80 nm, respectively, to form a cathode. After the degree of vacuum reached 1 × 10 ⁻⁴ Pa or less, metal deposition was started.

  Next, in order to produce a film, first, a solution for the film was produced. 6.32 g of polycarbonate was dissolved in 20.7 g of dichloromethane to prepare a 23.4 wt% solution. Next, Novec (manufactured by Sumitomo 3M), which is a fluorosurfactant, was mixed into this solution. The concentration of Novec in the mixed solution was 0.8 wt% to obtain a film solution. The obtained film solution was cast on a glass base so that the film thickness after film formation was about 150 μm in a constant temperature and humidity chamber with a humidity of 85%. After being left in an atmosphere of 85% humidity for 5 minutes, the film was dried by nitrogen flow to obtain a 20 mm × 20 mm film (film A) having a concavo-convex shape on the surface.

  Next, glycerin was applied as a pressure-sensitive adhesive to the surface of the support substrate opposite to the surface on which the light emitting layer was formed, and the film A was bonded to produce an organic EL device. The support substrate has a refractive index of 1.50, the adhesive has a refractive index of 1.45, and the film A has a refractive index of 1.58. The average film thickness of the film A is 230 μm.

<Production Example 3> Production of Organic EL Element Having Film An organic EL element having a film different from that of Production Example 2 was produced. In this Production Example 3, a commercially available film (film B) showing a high haze value (82%) was used. Since the film B has an adhesive layer, an organic EL element was produced by pasting the film B as it was without using an adhesive or the like.

<Comparative example 3> Preparation of organic EL element which has a film The organic EL element from which the film differs from the organic EL element of the preparation example 2 was produced.
As the film solution, the same solution as in Preparation Example 2 was used. In a constant temperature and humidity chamber with a humidity of 50%, the film solution was cast on a glass base so that the film thickness after film formation was about 220 μm. After being left in an atmosphere of 50% humidity for 5 minutes, the film was dried by nitrogen flow to obtain a 20 mm × 20 mm film (film C). This film C was attached to a support substrate in the same manner as in Production Example 2 using the same adhesive as in Production Example 2 to produce an organic EL device.

<Comparative example 4> Preparation of the organic EL element which has a film The organic EL element from which the film differs from the organic EL element of the preparation example 2 was produced.
As the film solution, the same solution as in Preparation Example 2 was used. In a constant temperature and humidity chamber with a humidity of 85%, the film solution was cast on a glass base so that the film thickness after film formation was about 220 μm. After leaving it in an atmosphere with a humidity of 85% for 5 minutes, the film was dried with a nitrogen flow to obtain a 20 mm × 20 mm film (film D) having an uneven shape on the surface. The obtained film D was attached to a support substrate in the same manner as in Production Example 2 using the same adhesive as in Production Example 2 to produce an organic EL device.

<Comparative example 5> Preparation of organic EL element which has a film The organic EL element from which the film differs from the organic EL element of the preparation example 2 was produced.
As the film solution, the same solution as in Preparation Example 2 was used. In a constant temperature and humidity chamber with a humidity of 85%, the film solution was cast on a glass base so that the film thickness after film formation was about 360 μm. After being left in an atmosphere of 85% humidity for 5 minutes, the film was dried by nitrogen flow to obtain a 20 mm × 20 mm film (film E) having an uneven shape on the surface. This film E was attached to a support substrate in the same manner as in Production Example 2 using the same adhesive as in Production Example 2 to produce an organic EL device.

<Observation of film surface>
The surfaces of the films used in Production Examples 2 and 3 and Comparative Examples 3, 4, and 5 were observed with a scanning electron microscope (SEM).
FIG. 3 is a diagram schematically showing a cross section of the film A produced in Production Example 2, FIG. 4 is a diagram schematically showing a cross section of the film B used in Production Example 3, and FIG. It is a figure which shows typically the cross section of the film C produced in the comparative example 3. FIG.

  In the film A produced in Production Example 2, it was confirmed that a hemispherical concave surface having an average diameter of 2 μm was formed on the surface of the film. It was confirmed that the concave surface was formed over the entire surface of the film A.

  Moreover, in the film B used for Preparation Example 3, it was confirmed that the surface of the film was formed in an uneven shape. It was confirmed that the concave surface was formed over the entire surface of the film B.

  Moreover, in the film C produced in the comparative example 3, it confirmed that the surface was a plane, without forming a concave surface on the surface.

  Moreover, in the film D produced in the comparative example 4, it confirmed that the hemispherical concave surface whose average diameter is 3 micrometers was formed in the surface of a film. Although the regularity of the arrangement of the concave surface was relatively low, it was confirmed that the concave surface was formed over the entire surface of the film D.

  Moreover, in the film E produced in the comparative example 5, it confirmed that the hemispherical concave surface whose average diameter was 4 micrometers was formed in the surface of a film. Although the regularity of the arrangement of the concave surface was relatively low, it was confirmed that the concave surface was formed over the entire surface of the film E.

  Table 3 shows the humidity when films were produced in Production Example 2 and Comparative Examples 3, 4, and 5, and the characteristics of the films used in Production Examples 2, 3 and Comparative Examples 3, 4, and 5.

  As shown in Table 3, it was confirmed that a film having a high haze value can be produced by controlling the humidity and the film thickness of the produced film. Moreover, when the film thickness of the produced film became thick, it confirmed that the diameter of the concave surface became large.

<Light extraction efficiency of organic EL element>
The light intensity of the organic EL element to which the films prepared in Production Examples 2 and 3 and Comparative Examples 3, 4, and 5 were bonded was compared with the light intensity of the organic EL element to which the film was not bonded. Table 4 shows the ratio of the light extraction efficiency obtained by dividing the light intensity of the organic EL element on which the film is bonded by the light intensity of the organic EL element on which the film is not bonded. The light intensity was measured by passing a current of 0.15 mA through the organic EL element, measuring the angle dependency of the emission intensity at that time, and integrating the emission intensity at all angles.

  In the organic EL element of Production Example 2, the light extraction efficiency was increased 1.5 times compared to before the film A was bonded. Furthermore, the organic EL element of Production Example 3 in which the film A of Production Example 2 and the film B having optical properties were bonded together also showed a significant increase in light extraction efficiency, similar to the organic EL element of Production Example 2. However, since the film C used for the organic EL element of Comparative Example 3 has almost no light scattering, no improvement in light extraction efficiency was observed. In Comparative Examples 4 and 5, no significant improvement in light extraction efficiency was observed.

  From this, it was revealed that a film having a high total light transmittance and a high haze value contributes to an improvement in light extraction efficiency. In particular, it was found that the light extraction efficiency is greatly improved when the haze value of the film is 70% or more. Thus, by providing the film which shows a predetermined optical characteristic, it confirmed that the extraction efficiency of light improved, and it confirmed that luminous efficiency improved as a result.

As described above, in Production Example 1, the light-emitting layer is formed of three light-emitting layers that emit red, green, and blue on the light-transmitting first electrode, and the red light is emitted from the anode toward the cathode. An organic EL device in which a light emitting layer, a green light emitting layer, and a blue light emitting layer are arranged in this order is manufactured, and the light emitting layer is composed of three light emitting layers that emit red, green, and blue, and these light emitting layers are directed from the anode toward the cathode. The effect of arranging the red light emitting layer, the green light emitting layer, and the blue light emitting layer in this order was confirmed.
In Production Examples 2 and 3, an organic EL element having a film provided on the outer surface opposite to the light-transmitting first electrode (anode) of the support substrate was manufactured, and it was confirmed that the light emission efficiency was improved. .

It is front sectional drawing which shows 1st Embodiment of the organic EL element of this invention. It is front sectional drawing which shows 2nd Embodiment of the organic EL element of this invention. It is a figure which shows typically the cross section of the film A produced in the manufacture example 2. FIG. It is a figure which shows typically the cross section of the film B used for the manufacture example 3. FIG. It is a figure which shows typically the cross section of the film C produced in the comparative example 3. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1,11 Organic EL element 2 Transparent support substrate 2a 1st main surface 2b 2nd main surface 3 Transparent anode (1st electrode)
4,12 Light-emitting part 5 Cathode (second electrode)
6,17 Light-emitting functional part 7,14 Protective film (upper sealing film)
14a 1st main surface 14b 2nd main surface 8,15 Film 9a, 19a Red light emitting layer 9b, 19b Green light emitting layer 9c, 19c Blue light emitting layer 13 Transparent cathode (1st electrode)
16 Anode (second electrode)
18 Support substrate A Film used in Production Example 2 B Film used in Production Example 3 C Film used in Comparative Example 3

Claims (10)

A first electrode having one of an anode and a cathode, and having light transmittance;
A second electrode disposed opposite to the first electrode and being the other of the anode and the cathode;
A light emitting part disposed between the first electrode and the second electrode and having three or more light emitting layers containing a polymer compound;
A film disposed on the outermost layer on the first electrode side with respect to the light emitting part, and
Each light emitting layer constituting the light emitting part emits light having a different peak wavelength, and the light emitting layer emitting light having a longer peak wavelength is disposed closer to the anode,
The film, wherein it is a light emitting side and the uneven surface of the opposite side, and a haze value of 70% or more, and Ri der total light transmittance of 80% or more (however, the ridges of the length and width A light control film having a plurality of ridge-like convex lens portions having a ratio of 5 or more and a top of the ridge forming a convex curved surface),
The surface of the film opposite to the light emitting layer side is constituted by a plurality of concave surfaces,
Organic electroluminescence device.   The organic light-emitting device according to claim 1, wherein the light emitting unit includes a light emitting layer that emits red light, a light emitting layer that emits green light, and a light emitting layer that emits blue light. A support substrate provided between the first electrode and the film;
The organic electroluminescence element according to claim 1, wherein the film is provided in contact with the support substrate. A protective film provided between the first electrode and the film;
The organic electroluminescence device according to claim 1, wherein the film is provided in contact with the protective film.   When the voltage applied between the anode and the cathode is changed, the width of the change between the coordinate value x and the coordinate value y in the chromaticity coordinates of the light extracted outside is 0.05 or less, respectively. The organic electroluminescent element according to claim 1, wherein A planar light source comprising the organic electroluminescence element according to any one of claims 1 to 5.   An illuminating device provided with the organic electroluminescent element as described in any one of Claim 1 to 5.   A display apparatus provided with the organic electroluminescent element as described in any one of Claim 1 to 5. A first electrode that is one of an anode and a cathode, has a light transmission property, and is disposed opposite to the first electrode, and a second electrode that is the other of the anode and the cathode And a light emitting part disposed between the first electrode and the second electrode and having three or more light emitting layers containing a polymer compound, and an outermost layer on the first electrode side with respect to the light emitting part. A method for producing an organic electroluminescent device comprising a film,
Forming each light emitting layer sequentially by a coating method so that the light emitting layer emitting light having a long peak wavelength is disposed closer to the anode;
A film forming step of forming a film on the opposite side of the light emitting part side, having a concavo-convex shape, having a haze value of 70% or more and a total light transmittance of 80% or more,
In the film forming step, a solution containing the material to be the film is applied onto the surface on which the film is formed so that the thickness of the film is in the range of 100 μm to 200 μm, and the applied solution is applied. After holding in an atmosphere with a humidity of 80% to 90%, it is dried to form a film.
Manufacturing method of organic electroluminescent element. The manufacturing method of the organic electroluminescent element of Claim 9 in which the solution containing the material used as the said film contains surfactant.

Images